We report here the probable detection of an emission line of Si IX that was observed from an open C130 aircraft over the Pacific Ocean during the 1998 total solar eclipse. Although the IR data themselves are inconclusive because of the uncertainty in the precise central wavelengths of the narrowband filters during the eclipse, the consistency of the measured IR limb excess with simultaneous EUV emission measured by SOHO/Coronal Diagnostic Spectrometer and the EUV Imager Telescope support our detection claim. This line appears to be the brightest IR coronal line yet observed, and its existence may significantly improve future prospects for obtaining optical coronal magnetic field measurements.
The solar eclipse on February 26, 1998, was observed from an aircraft operated by the Research Aviation Facility of the National Center for Atmospheric Research. The observations cover the near infrared spectral range and were made at an altitude of almost 6 km above the Pacific about 800 km southwest from Panama City. Aside from spectroscopic observations of coronal emission lines, the solar F-corona was observed in the J and K-band over a field of view of 7°. A preliminary view on the data shows no indication for the existence of pronounced brightness features in the solar F-corona.
We present observations of the solar corona in white light at the time of the 1991 July 11 total solar eclipse together with daily observations made during the interval 1991 June 12 to August 16 designed to provide a synoptic context in which data from the total solar eclipse can be interpreted. Included in the daily observations are those from the Mark-III K-coronameter of the Mauna Loa Solar Observatory as well as photographic records of the sun in Halpha made from the same site. Combining these data with the eclipse observation, we estimate a probable global density distribution of the corona at the time of the eclipse. This indicates that although the eclipse occurred soon after the most recent solar activity cycle maximum, the corona was already organized in a tilted dipole configuration.
